Simplified boundary layer control for a jet



'ROURKE SIMPLIFIED BOUNDARY LAYER CONTROL FOR A JET June 30, 1959 Filed Aug. 17. 1956 INVENTOR. ode;

United States Patent SIMPLIFIED BOUNDARY LAYER CONTROL FOR A .l'ET

Neil ORourke, La Jolla, Calif., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application August 17, 1956, Serial No. 606,941

3 Claims. (Cl. 230-95) This invention relates to an improvement in jet pumps. The improvement basically provides for an increase in the etficiency of the jet pump through the institution of a boundary layer control system for such pumps.

The object of this invention therefore is a novel type of jet pump incorporating therein a boundary layer control system.

A secondary object of this invention is a simplified form of boundary layer control in a jet pump thereby maintaining such a pump simple in construction consequently simplifying production problems.

Other objects and advantages will be readily apparent to those skilled in the art from an examination of the specification and enclosed drawing wherein the single figure depicts in a cross-sectional view a conventional jet pump with the boundary layer control incorporated therein.

In the figure, pump 1 comprises a suction case or outer enclosure 2 encircling therein a concentric mixing tube 5. The tube is joined to the case by an inlet cone 3 at the front end of the pump and an outlet difluser cone 4 at the rear of the pump with the two cones joined to the extremities of the two shells.

At the front end of the pump, a high pressure inlet 8 is supported concentrically with the two shells by means of struts 16. The high pressure tube may comprise any form but in the instant invention consists of a tube 9 merging into a V section 11 to thereby form a Y; tubular means 12 form extension outlets of the Y section. Located at the exit extremities of the Y are rings 13 and 17 providing a constriction at each high-pressure outlet, tubular means 12 in combination with rings 13 and 17 thus functioning as injection nozzles.

All the elements illustrated are either circular or conical in cross-sectional area thereby obviating the necessity of providing an additional end or cross-sectional view.

The entire forward section of the diffuser cone is perforated by a multiple series of openings or ports 7 creating a boundary layer suction section for the intermediate pressure fluid.

At the inlet end of the mixing tube approximately adjacent the outlet end of annularly arranged, the venturi, a plurality of large openings 6 are punched or drilled in the wall of the tube ofiering communication between the passageway 18 and the inner portion of the mixing tube.

In operation, the low pressure fluid (14) is pumped through the mixing tube by the action of the high pressure fluid (15) flowing from the tubular means 12 into the inlet cone 13 a predetermined distance upstream of the openings 6 in the wall of the mixing tube or, stated in another manner, by the action of the high pressure fluid exiting from the venturi section. Within the tube 5, the two fluids are intermixed attaining a pressure intermediate the high and low pressures. The mixed fluid passes through the diffuser where it is conducted further to a place of use.

In exiting via the diffuser cone, the mixed fluid has a certain proportion of the fluid adhering to the wall of the diffuser. However by the use of a multiple series of ports 7 in the wall, the layer is destroyed and a flow is created in passage 18 toward the front of the pump unit. As is Well known from Bernoullis theorem, the low pressure area adjacent port openings 6 within the mixing tube creates a suction effect for this induced flow causing the sucked boundary layer fluid to rejoin the main stream of fluid in tube 5.

With the use of such boundary layer control, the diffuser losses, which constitute a major jet pump loss, are substantially reduced; at the same time, a lower pressure can be maintained in the mixing tube thereby permitting higher pumped quantities and lower turbulence losses due to the differential of driving and driven fluid velocities.

While the specific construction has been applied to a jet pump using gas as the driving and driven fluids, it is understood that pumps using fluids other than gas may utilize the above boundary control principle.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In a jet pump adapted to effect the movement of a low pressure fluid by a high pressure fluid, a cylindrical outer shell member, a cylindrical inner shell member carried within said outer shell member and forming a mixing chamber and passageway for said high and low pressure fluids, said inner shell member having a plurality of annularly arranged ports therein adjacent the inlet end thereof and being operable to define a passageway between said inner and outer shell members, conical means connecting said outer shell member to said inlet end of said inner shell member and defining an inlet for said low pressure fluid, a plurality of tubular in jection nozzles carried within said conical inlet means for injecting said high pressure fluid into said conical inlet means a predetermined distance upstream of said inlet end of said inner shell member, means connecting said injection nozzles to said conical inlet means and thereby supporting said injection nozzles in a fixed position within said conical inlet means, and a conical-shaped diffuser member connecting said outer shell member to the outlet end of said inner shell member and defining a fluid outlet for said high and low pressure fluids passing through said inner shell memher, said diffuser member having a plurality of ports therein in communication with said passageway between said inner and outer shell members whereby the boundary layer of fluid in said diffuser member is conducted through said passageway and discharged into said inner shell member through said annularly arranged ports therein.

2. In a jet pump as claimed in claim 1 wherein said inner shell member is concentrically positioned within said outer shell member.

3. In a jet pump as claimed in claim 1 wherein two injection nozzles are utilized and said nozzles are fixedly positioned within the conical inlet means to inject high pressure fluid longitudinally of said conical inlet means and said inner shell member.

References Cited in the file of this patent UNITED STATES PATENTS 1,421,840 Schmidt July 4, 1922 2,000,741 Buckland May 7, 1935 2,589,945 Leduc Mar. 18, 1952 

